Dietary Supplements

Definition

Purpose

Description

Precautions

Interactions

Complications

Parental concerns

Resources

Definition

In the United States, dietary supplements are defined by the 1994 Dietary Supplement Health and Education Act as products that are not used exclusively as food, but are intended to be consumed in addition to an individual’s diet. The law states that dietary supplements are taken by mouth and contain.

Drug interactions

source: Office of Dietary Supplements, National Institutes of Health, U.S. Department of Health and Human Services.

(Illustration by GGS Information Services/Thomson Gale.)

one or more dietary ingredients. Examples of dietary ingredients include vitamins, minerals , herbs or other biological material, amino acids, and enzymes. Dietary supplements are sold in the form of tablets, capsules, powders, liquids, extracts, or teas. Products sold as dietary supplements are required to be clearly labeled as such.

Purpose

Dietary supplements serve a wide range of purposes. Some of these are medically appropriate, while others may do nothing or harm the individual. Reasons for taking dietary supplements include:

• Replacing a necessary substance not found in large enough quantities in the diet
• Preventing or decreasing the risk of developing a disease or condition
• Boosting the immune system and improving general health
• Boosting energy levels
• Improving mental or physical performance
• Stimulating weight loss
• Reducing symptoms of a disease or health condition

Description

Dietary supplements comprise a variety of products ranging from familiar multivitamins found in every supermarket to exotic botanicals such as the South African herb hoodia . Millions of Americans take dietary supplements daily; their use has become increasingly common since the 1990s. The United States Food and Drug Administration (FDA) estimates that in 1999 more than 12 million Americans were taking ephedra , a weight-loss supplement that was later banned because it can cause serious side effects. Due to the large number of different supplements and their range of uses, testing and regulation of these products is difficult and often ineffective.

Dietary supplements and the law

The FDA regulates dietary supplements under the 1994 Dietary Supplement Health and Education Act (DSHEA). At the time the act was passed, legislators believed that because many dietary supplements come from natural sources such as plants and have been used for hundreds of years by practitioners of complementary and alternative medicine (CAM), these products did not need to be as rigorously regulated as prescription and over-the-counter drugs used in conventional medicine.

DSHEA regulates supplements in the same way food is regulated. Like food manufacturers, manufacturers of dietary supplements do not have to prove that a supplement is either safe or effective before it can be sold to the public. Manufacturers of conventional pharmaceutical drugs, however, must prove both safety and effectiveness in humans before a new drug is approved for use. With dietary supplements, the burden of proof falls on the FDA to show that the supplement is either unsafe or ineffective before the supplement can be restricted or banned. Information about a supplement’s safety and effectiveness is normally gathered only after people using the product develop health problems or complain that the product does not work. Initially, supplement manufacturers were not required to report consumer complaints of complications or side effects to the FDA. However, beginning in 2007, a federal law requires all manufacturers of dietary supplements and over-the-counter drugs to report consumer complaints of adverse events (negative side effects) to the FDA. This makes accumulating information on the safety of these products faster and easier.

Dietary supplements are required to be clearly labeled with the word “supplement.” The label must also show the volume or weight of the contents, the serving size, a list of dietary ingredients and non-dietary ingredients (e.g., artificial color, binders, fillers, flavorings), the name of the manufacturer, packer, or distributor, and directions for use. If the supplement is an herb, the label must contain its scientific name.

Unlike conventional drugs, the label for a dietary supplement does not have to provide statements about possible side effects. However, dietary supplements are not legally allowed to claim they can “cure,” “treat,” “mitigate,” “prevent,” or “diagnose” a specific disease. They may make the following claims:

• Health claims—Statements indicating a relationship between an ingredient in the supplement and the reduction in the risk of developing a disease or condition. (e.g., Increased intake of folic acid by pregnant women helps reduce the risk of neural tube defects in their offspring.)
• Nutrient content claims—Statements describing the amount of supplement in the product and may contain words such as “high in,” “good source of,” “fortified,” “enriched,” or “high potency.”
• Structure or function claims—Description of how the supplement may affect organs or systems in the body without mentioning a specific disease or condition. (e.g., Calcium builds strong bones.) Labels with structure or function claims must also contain the words “This statement has not been evaluated by the FDA. This product is not intended to diagnose, treat, cure, or prevent any disease.”

Manufacturers of supplements are required to follow federal Good Manufacturing Practices (GMPs) that regulate sanitary and other conditions under which these products are prepared, packaged, and stored. These GMPs are much less stringent than those that regulate the manufacture of conventional drugs. They do not, for example, assure that the amount of active ingredient in each pill or capsule of a dietary supplement is the same. Some supplement manufacturers try to assure consistency of their product by making sure each batch contains the same amounts of active ingredients. This type of standardization is not required by law, and the word “standardized” on the label is not an indication that the product meets any legal requirements as to quality or consistency of contents.

Dietary supplements in conventional medicine

Conventional medicine, also called Western or mainstream medicine, is practiced by licensed medical doctors (MD) and doctors of osteopathy (DO), dentists (DDS or DMD), registered nurses (RN), licensed practical nurses (LPN), pharmacists, and similar health care professionals. Some dietary supplements are routinely used as an accepted part of conventional medicine. The most common of these are vitamin and mineral supplements taken in accordance with established dietary reference intakes (DRIs). DRIs are a set of values for different nutrients that indicate the daily amount of that nutrient necessary to meet the needs of most individuals, as well as the largest amount of the nutrient that can be consumed daily without harmful effects. Other supplements, such as folic acid, are prescribed for pregnant women in order to decrease the risk of neural tube defects in their offspring. Still other supplements, such as enzymes, may be given when the body fails to produce adequate amounts of the enzyme as the result of a genetic disorder such as cystic fibrosis. When taken under supervision of a conventional health care professional, dietary supplements tend to be extremely safe.

Dietary supplements in complementary and alternative medicine

Most dietary supplements are used within a system of complementary and alternative medicine (CAM). Complementary medicine uses treatments that are not part of conventional medicine to supplement conventional medicine. Alternative medicine uses treatments that are not part of conventional medicine as a complete replacement for conventional medicine. Alternative medicine includes well-established treatment systems such as homeopathy, traditional Chinese medicine, and Ayurve-dic, or traditional Indian medicine, as well as newer fad-driven treatments. Many CAM treatments have their roots in tradition and folklore.

Herbs are some of the most common dietary supplements used in CAM. Many have been used for hundreds of years and show evidence of effectiveness. Others are ineffective or may harm the individual either directly or when used as a replacement for conventional drugs and treatments whose effectiveness has been proven. Vitamin and mineral supplements used as part of conventional medicine become part of the CAM system when they are used in mega-doses that far exceed DRI values or when they are used to prevent or treat a specific condition (e.g., vitamin C to prevent colds). Likewise, enzymes and amino acids that have specific uses within conventional medicine become part of the CAM system of dietary supplements when they are used in non-conventional ways or in non-standard doses. Some dietary supplements, such as bee pollen, are used exclusively in CAM.

Precautions

It is difficult to determine whether dietary supplements are safe or effective because of the way they are regulated. Many of the studies done on supplements are poorly designed, have a small sample size, or are sponsored by the manufacturer of the supplement, making the results questionable. Natural Standard is an independent organization that evaluates studies, scientific evidence, and expert opinion on CAM treatments and therapies and makes impartial judgments concerning their safety and effectiveness. The National Center for Complementary and Alternative Medicine is a government organization within the National Institutes of Health that investigates CAM treatments and runs rigorous clinical trials to determine safety and effectiveness.

Individuals interested in using dietary supplements should consult their health care provider and other reputable sources of information before taking any new supplements. Pregnant or breastfeeding women should be especially careful to discuss the supplements they may want to take with their health care provider. Many herbs and other dietary supplements cross the placenta or are secreted into breast milk and may affect the fetus or nursing baby. In addition, care should be taken in giving children dietary supplements. Few studies have been done specifically on children and the recommended dosage for adults may be harmful to children. As with any medication, more is not necessarily better. Overdose is a common cause of adverse side effects in dietary supplements. In the event of side effects, the supplement should be stopped immediately and the side effects reported to a health care professional.

Interactions

Dietary supplements may interact with both conventional drugs and other herbs or dietary supplements. Individuals should seek information about specific interactions from their health care provider. Many dietary supplements should be stopped several days before surgery to reduce the risk of excess bleeding.

Complications

There is strong evidence that some dietary supplements can cause serious harm or death. For example, the weight-loss supplement ephedra was found to have contributed to the death of the Baltimore Oriole’s pitching prospect Steve Belcher in 2003. The FDA later banned ephedra-containing supplements. According to the American Association of Poison Control Centers, there have been over 62,000 reports of vitamin poisonings, over 23,000 cases linked to minerals, and over 23,000 reports linked to herbs. Twenty-seven deaths were attributed to dietary supplements in 2005, of which 13 were attributed to herbs. It should be remembered that “natural” does not mean safe; for example, many wild mushrooms are completely natural and cause death when eaten.

Complications may arise from dietary supplements themselves or their misuse or poor regulation of the manufacturing process. This is especially true of those supplements imported into the United States.

KEY TERMS

Alternative medicine —A system of healing that rejects conventional, pharmaceutical-based medicine and replaces it with the use of dietary supplements and therapies such as herbs, vitamins, minerals, massage, and cleansing diets. Alternative medicine includes well-established treatment systems such as homeopathy, Traditional Chinese medicine, and Ayurvedic medicine.

Amino acid —Molecules that are the basic building blocks of proteins.

Botanical —An herb; a dietary supplement derived from a plant.

Complementary medicine —Includes many of the same treatments used in alternative medicine, but uses them to supplement conventional drug and therapy treatments, rather than to replace conventional medicine.

Conventional medicine —Mainstream or Western pharmaceutical-based medicine practiced by medical doctors, doctors of osteopathy, and other licensed health care professionals.

Enzyme —Proteins that change the rate of a chemical reaction within the body without themselves being used up in the reaction.

Herb —A plant used in cooking or for medical purposes. Examples include Echinacea and ginseng.

Mineral —An inorganic substance found in the earth that is necessary in small quantities for the body to maintain a health. Examples include zinc, copper, and iron.

Vitamin —A nutrient that the body needs in small amounts to remain healthy but that the body cannot adequately manufacture for itself and must acquire through diet.

from developing countries. Independent laboratory analyses of dietary supplements have found:

• Contamination with pesticides
• Contamination with heavy metals
• Presence of ingredients not listed on the label
• Amount of dietary ingredient not the same as the amount listed on the label

Some health professionals believe the number of complications related to dietary supplements is severely under-reported. This should improve with the 2007 requirement that dietary supplement manufacturers report adverse side effects to the FDA.

Parental concerns

Parents should be aware that the RDA and UL for vitamins and minerals are much lower for children than for adults. Accidental overdose may occur if children are give adult vitamins or dietary supplements.

Resources

BOOKS

Davis, W. Martin. Consumer’s Guide to Dietary Supplements and Alternative Medicines. Binghamton, NY: Pharmaceutical Products Press, 2006.

PDR for Herbal Medicines, 3rd ed. Montvale, NJ: Thompson Healthcare, 2004.

Pierce, Andrea. The American Pharmaceutical Association Practical Guide to Natural Medicines. New York: William Morrow, 1999.

Wildman, Robert E. C., ed. Handbook of Nutraceuticals and Functional Foods, 2nd ed. Boca Raton, FL: CRC/ Taylor&Francis, 2007.

PERIODICALS

Hurley, Dan. “Benign View of Diet Supplements Fading.” San Jose Mercury News. (January 28, 2007).

Saper, R.B., D.M. Eisenberg, and R.S. Phillips. “Common Dietary Supplements for Weight Loss.” American Family Physician 70, no. 9 (2004): 1731-8.

ORGANIZATIONS

Alternative Medicine Foundation. P.O. Box 60016, Potomac, MD 20859. Telephone: (301) 340-1960. Fax: (301) 340-1936. Website: <http://www.amfoundation.org>.

National Center for Complementary and Alternative Medicine Clearinghouse. P.O. Box 7923, Gathersburg, MD 20898. Telephone: (888) 644-6226. TTY: (866) 464-3615. Fax: (866) 464-3616. Website: <http://nccam.nih.gov>.

Natural Standard. 245 First Street, 18th Floor, Cambridge, MA 02142. Telephone: (617) 444-8629. Fax: (617) 444-8642. Website: <http://www.naturalstandards>.

Office of Dietary Supplements, National Institutes of Health. 6100 Executive Blvd., Room 3B01, MSC 7517, Bethesda, MD 20892-7517 Telephone: (301) 435-2920. Fax: (301) 480-1845. Website: <http://dietary-supplements.info.nih.gov>.

OTHER

“Dietary Supplements: Background Information.” National Institutes of Health, Office of Dietary Supplement. April 12, 2006. [cited May 5, 2007]. <http://dietary-supplements.info.nih.gov/factsheets/dietarysupplements.asp>.

“Herbal Medicine.” Medline Plus. U.S. National Library of Medicine. March 11, 2007. [cited May 5, 2007]. <http://www.nlm.nih.gov/medlineplus/herbalmedicine.html>.

“Herbal Supplements: Consider Safety, Too.” National Center for Complementary and Alternative Medicine. December 2006. [cited May 5, 2007]. <http://nccam.nih.gov/health/supplement-safety>.

“How to Know What Is Safe: Choosing and Using Dietary Supplements.” American Cancer Society. January 28, 2005. [cited May 5, 2007]. <http://www.cancer.org/docroot/ETO/content/ETO_5_3x_How_to_Know_What_Is_Safe_Choosing_and_Using_Dietary_Supplements.asp>.

Mayo Clinic Staff. “Herbal Supplements: How They Can Interfere With Surgery.” MayoClinic.com. November 23, 2005. [cited May 5, 2007]. <http://www.mayoclinic.com/health/herbal-supplements/SA00040>.

Mayo Clinic Staff. “Weight-loss Pills: What Can Diet Aids Do for You?” MayoClinic.com. March 10, 2006. [cited May 5, 2007]. <http://www.mayoclinic.com/health/weight-loss/HQ01160>.

Tish Davidson, A.M.

Dietary supplements

Definition

Dietary supplements are products designed to ensure that a person gets adequate amounts of essential nutrients or to help promote optimal health and performance, especially for a person who does not consume a variety of foods. Dietary supplements are not intended to be used to treat, mitigate, prevent, or cure disease. Dietary supplements include not only vitamins and minerals but also such substances as herbals, botanicals, amino acids, enzymes, and animal extracts. Dietary supplements can come in pill, capsule, powder, siftgel, gelcap, tablet, or liquid forms. Dietary supplements can be purchased without a prescription through retail outlets, including grocery and drug stores, general merchandise retailers, natural food and specialty health and nutrition stores. Many dietary supplements can also be purchased on-line through the Internet. Supplements must have a Supplement Facts label on the product to differentiate supplements from food products or over-the-counter (OTC) drugs.

Description

Nutritional needs of persons change after the age of 50. These needs should be met by making informed food choices and eating a wide variety of foods, but in some cases, supplements and fortified foods may be needed to obtain appropriate amounts of nutrients. Older adults may not eat three meals a day or may have a restricted diet (for example, not eating meat, milk or milk products or sufficient fruits and vegetables), resulting in malnutrition . It may be a benefit to use vitamin, mineral or other dietary supplements to ward off side effects of poor nutrition. The selection of appropriate supplements should be made in cooperation with a health care provider or registered dietician . Dietary supplements should never be taken in doses higher than recommended. Manufacturers of dietary supplements are allowed to make claims concerning the health, nutritional content, and structure/function according to the following limitations:

• Health claims that describe a relationship between a dietary supplement ingredient and reducing risk of a disease or health-related condition
• Nutrient content claims referring the the percentage of Daily Value (DV) of the nutrient that the supplement provides
• A structure/function claim describing how a product may affect the organs or systems of the body, but cannot mention a specific disease.

Vitamin supplements provide extra micronutrients needed by the body for growth, digestion, and nerve function, for metabolism of carbohydrates , fats, and proteins to provide energy, and for cellular repair. Vitamins are recommended for persons who may not be getting sufficient amounts from their diet. Examples of supplements that may be recommended by the U.S. government for persons over the age of 50 include vitamin B in its crystalline form (as found in fortified breakfast cereals or in supplements) and vitamin D from vitamin D-fortified foods and/or supplements (as older adults may not get sufficient exposure to sunlight). Other common vitamin supplements include vitamin A, vitamin C , and vitamin E .

Mineral supplements provide micronutrients that are found in bones and teeth. Minerals aid in creating new cells and enzymes, distribute fluids, controlling nerve impulses, and carrying oxygen to cells and carbon dioxide from cells. Examples of mineral supplements include calcium , copper, iron, magnesium, selenium, and zinc . Senior citizens may need extra calcium as they age to maintain strong bones and reduce bone loss.

Herbs, also referred to as botanicals, have been used for centuries as healing therapies. The World Health Organization has estimated that 80% of the world's population still uses herbs as medical therapies.

Herbal supplements are usually considered to have medicinal value. Herbal supplements are manufactured as extracts of fresh or dried products, tablets, capsules, powders, teas, roots, or leaves. They consist of a group of chemicals or a single chemical isolated from a plant and are used to maintain or improve health in a specific part or organ of the body. The best supplements will contain standardized extracts, ensuring consistency from batch to batch. The use of single herb supplements rather than a combination of herbs will allow a person to evaluate better whether a particular herb is effective. Examples of herbal supplements include black cohosh, suggested for malaise, gynecological conditions, kidney disorders, rheumatism, and hives; echinacea, suggested for upper respiratory conditions; ginger, suggested for nausea, arthritis, osteoarthritis , and joint and muscle pain ; and saw palmetto , suggested for bladder and kidney functioning. Before using herbal supplements, especially if a person is taking other medications, the patient's physician should be consulted.

A consumer of dietary supplements should attempt to learn as much about supplements as possible. Information that may help to evaluate the quality of a specific supplement include:

• Is it an established brand?
• What is the specific herbal information, including Latin name?
• What type of fillers are used?
• Is there customer service information available, including toll-free phone number and/or web site?
• What are the recommendations for use? How much and how often?
• What is the amount per serving and percent daily value (if established) of the supplement?
• Are there additives (especially allergens) present in the formulation?
• Are there any warnings for use?
• What is the lot number?
• What is the expiration date?
• What are the storage instructions?

There are several independent organizations that offer seals of approval that may be displayed on certain dietary supplement products. These seals indicate that the supplement has passed the organization's quality tests for potency and the presence of contaminants, providing assurance that the product was properly manufactured, that is contains the ingredients listed on the label, and that it does not contain harmful level of contaminants. However, the approval does not mean that the product is safe or effective. Examples of organizations that test dietary supplements are ConsumerLab.com and U.S. Pharmocopeia.

The U.S. National Institutes of Health (NIH) have developed a series of vitamin and mineral fact sheets that provide scientifically sound and reliable information about dietary supplements. These fact sheets are available online. Information on dietary supplements from Medline Plus, a service of the U.S. National Library of Medicine and NIH, is also available. The Office of Dietary Supplements of the NIH has two databases available where information concerning research projects pertaining to dietary supplements can be obtained: the CARDS Database (Computer Access to Research on Dietary Supplements) and the IBIDS Database (International Bibliographic Information on Dietary Supplements). Both databases can be accessed from the Office of Dietary Supplements web site. The National Center for Complementary and Alternative Medicine provides information on supplements at their website.

The U.S. National Library of Medicine maintains the Dietary Supplements Labels Database with information concerning ingredients in more than 2,000 brands of dietary supplements. Information is also provided on the health benefits claimed by the man-ufacturers. Information on warnings and recalls from the U.S. FDA related to specific ingredients and supplement brands are also available.

Recommended dosage

Combined intake from supplements as well as from fortified foods such as certain cereals and drinks could result in health problems by exceeding safe levels of the active ingredients. A person who chooses to use dietary supplements should become informed on safe dosages.

Precautions

Scientific evidence to support the benefits of some dietary supplements (especially vitamins and minerals) is well-established for certain health conditions, while benefits for other types of supplements need further study. The use of supplements in the United States is regulated by the U.S. Food and Drug Administration (FDA). The FDA does not analyze the contents of dietary supplements, but supplement manufacturers must meet the requirements of the the U.S. FDA Good Manufacturing Practices (GMP) for food, which specifies conditions under which products must be prepared, packed, and stored. Unlike for drug approvals, research studies using human subjects is not necessary before a supplement is marketed. It is the responsibility of the manufacturers and distributors to ensure that there products are safe and that their label claims are accurate and truthful. If the FDA finds a supplement to be unsafe once it is on the market, then the FDA can take action against the manufacturer and/or distributor by issuing a warning or requiring that the product be removed from the marketplace.

Also, unlike for drugs, the manufacturer does not have to prove that the supplement is effective. The manufacturer may say that a product addresses a nutrient deficiency, supports health, or reduces the risk of developing a health problem. However, if the manufacturer does make a claim, it must also include the following statement: This statement has not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease.

QUESTIONS TO ASK YOUR PHARMACIST

• What is this supplement for and what are its intended benefits?
• How, when, or for how long should I take this supplement
• Is taking a supplement an important part of my total diet?
• Are there precautions, warnings, or dosage limits that I should know about?
• Are there any known side effects?
• Are there any foods, medications (OTC or prescribed), or other supplements that I should avoid while taking this supplement?
• If I am scheduled for surgery, should I be careful about what supplements I am taking?
• Can I afford this supplement? Are effective generic versions available?

Consumers should be careful in believing that even if a supplement does not help that it will not be harmful. Many ingredients in dietary supplements can be very strong acting chemicals and may be harmful when consumed over long periods of time or in conjunction with other supplements or medications. Some supplements are known to be toxic, such as chapparal (linked to liver damage) and yohimbe (a sexual stimulant link to heart and respiratory problems). The words natural or herbal do not necessarily mean that a supplement is safe. Many dietary supplements can be expensive, so it is important to consult with a physician, nurse, dietician, pharmacist, or health care giver before purchasing supplements, especially when combining them with other supplements or medicines.

Consumers of dietary supplements should also be careful in evaluating claims of health benefits (that is, buyer beware). Accurate health advice is based on long-term research and not on a single study or anecdotal evidence. If something sounds too good to be true, it probably is. Examples of exaggerated statements include those that claim that the supplement is a cure-all, quick fix, miraculous product, or can treat diseases, those that claim the product is totally safe or definitely has no side effects, those that use overly impressive terminology, and those that express that there is only limited availability and advanced payment is required.

If there are concerns about a supplement, consumers are advised to check with the manufacturer to find out if there is information available to support claims for the product as well as information on safety or effectiveness of the product ingredients. The manufacturer can also provide information on adverse reports from consumers who have used the product. If persons have adverse effects from the use of dietary supplements, they should stop taking the supplement and they or their health care provider or their care giver should report these effects to the FDA's Med-Watch program at 1-800-FDA-1088, by fax at 1-800 FDA-0178, or online at [http://www.fda.gov/medwatch/how.htm].

Side effects

In some cases, dietary supplements may have unwanted or unexpected side effects, especially if taken before surgery or with other dietary supplements. Filler ingredients in supplements may also result in side effects, especially if the product contains common allergens, such as wheat, corn, or milk.

Interactions

Although certain dietary supplements may be helpful for older people, they may also at times not be beneficial. Taking a combination of supplements with prescribed medications may result in harmful and even life-threatening conditions. For example, coumadin (a prescription medicine), ginkgo biloba (an herbal supplement), aspirin (an OTC drug), and Vitamin E (a vitamin supplement) all can result in thinning of the blood. Taking any of these products together can increase the potential for internal bleeding or stroke . St. John's wort can result in potential adverse effects by reducing the effectiveness of prescription medications for heart disease , depression , seizures, certain cancers, or HIV.

Dietary supplements may also have adverse effects before, during, and after surgery by interacting with prescription medications, resulting in change of heart rate, blood pressure , or bleeding. The physician may request that the patient stop taking dietary supplements two to three weeks before surgery to avoid potentially harmful supplement and drug interactions .

Caregiver concerns

The care giver of an elderly person should be aware of the types and amounts of supplements the person is taking and work with health care providers to make sure that the supplements are appropriate and will not result in adverse effects when used in combination with other supplements or with other medications, both OTC and prescribed.

KEY TERMS

Fortified foods —A method used to provide the required nutrients in populations where a certain vitamin or mineral is not available or not available in sufficient quantities. The required nutrient(s) are added to a staple food, such as flour or salt, or it is added it to drinking water, or to some other food / drink that is consumed. In this way, the population receives the nutrient(s) that they would otherwise lack.

Micronutrient —A vitamin or mineral that the body must obtain from outside sources. Micronutrients are essential to the body in small amounts because they are either components of enzymes or act as coenzymes in managing chemical reactions.

Resources

BOOKS

Mason, Pamela. Dietary Supplements, 3rd Edition. London, UK: Pharmaceutical Press, 2007.

Novartis Foundation. Dietary Supplements and Health. Hoboken, NJ: John Wiley and Sons, Inc., 2007.

Physician's Desk Reference Staff. PDR for Nonprescription Drugs, Dietary Supplements, and Herbs, 2008. Stamford, CT: Thomson Healthcare, 2007.

Schulman, Robert and Dean, Carolyn. Solve It with Supplements: The Best Herbal and Nutritional Supplements to Help Prevent and Heal More than 100 Common Health Problems. Emmaus, PA: Rodale Books, 2006.

Smith, Pamela Wartian. What You Must Know About Vitamins, Minerals, Herbs, & More: Choosing the Nutrients that are Right for You. City Park, NY: Square One Publishers, 2008.

Talbott, Shawn M., and K. Hughes. The Health Professional's Guide to Dietary Supplements. Philadelphia, PA, 2006.

ORGANIZATIONS

Office of Dietary Supplements, National Institutes of Health, Suite 3B01, 6100 Executive Boulevard, Bethesda, Maryland, 20892, (301) 435-2920, (301) 480-1845, ods@nih.gov, http://ods.od.nih.gov.

Office of Nutritional Products, Labeling, and Dietary Supplements, Center for Food Safety and Applied Nutrition, Food and Drug Administration, 5100 Paint Branch Parkway, College Park, MD, 20740, (301) 436-2373, (888) 723-3366, (301) 436-2639, http://www.cfsan.fda.gov/̃dms/onplds.html.

Judith L. Sims

Alternative Medicines and Therapies

Alternatives to conventional medical care are increasingly popular in the United States, and their growing use by consumers represents a major trend in Western medicine. Alternative therapies appear to be used most frequently for medical conditions that are chronic , such as back pain, arthritis , sleep disorders, headache, and digestive problems. Surveys of U.S. consumers have shown that more people visit alternative practitioners each year than visit conventional primary-care physicians. Consumers do not necessarily reject conventional medicine, however. Many simply feel that alternative modalities offer complementary approaches that are more in line with their personal health philosophies.

Alternative Medicine, Complementary Medicine, and Integrative Medicine

The terms alternative medicine and alternative therapies refer to those medical practices that are not considered to be conventional medicine, as practiced in the United States. Other cultures, however, may use one or more of these approaches regularly, and, in fact, many have done so for thousands of years. Most people in the United States who use alternative medicine do so to complement conventional approaches. For example, in addition to using anti-inflammatory drugs to ease muscle pain, they may also use massage, chiropractic , and/or osteopathic manipulation. This practice of complementing conventional medicine with alternative approaches has given rise to the term complementary medicine. Presently, alternative medicine is most commonly referred to as complementary and alternative medicine (CAM). As conventional medical practitioners become familiar with alternative approaches, these approaches are being integrated into conventional medicine, which is giving rise to integrative medicine, in which a combination of therapies representing the best of conventional and alternative medicine is used.

Types of CAM Modalities

The National Center for Complementary and Alternative Medicine divides the various CAM modalities into five categories: (1) alternative medical systems, (2) mind-body interventions, (3) biologically-based treatments, (4) manipulative and body-based methods, and (5) energy therapies. These modalities include a wide variety of approaches, from acupuncture to nutrition to meditation to chiropractic.

Alternative medical systems include medical practices that are traditional in other cultures, such as the ayurvedic medical system of India, Chinese traditional medicine, and traditional Native American and Hawaiian medicine.

Mind-body interventions recognize the connection between the physical body and the spiritual self, and include practices such as meditation, prayer, and music therapy. Biologically-based modalities are primarily nutrition-related and vary from special diets such as the macrobiotic diet to the inclusion of dietary supplements in the diet. Body-based methods involve hands-on manipulation of the body, and include such modalities as massage and chiropractic. The energy therapies are based on the concept that the body has an energy field that can be manipulated to promote healing.

Included among the nutrition approaches that make up the biologicallybased modalities is the use of dietary supplements. Dietary supplements may be botanical (herbal ) supplements or nutritional supplements, which include vitamins , minerals , antioxidants , enzymes , metabolites , nonprescription hormones , glandular extracts, and various amino acids , fatty acids , and other nutrients .

The Dietary Supplement Health and Education Act of 1994

Dietary supplement usage in the United States has increased significantly since the passage in 1994 of the Dietary Supplement Health and Education Act (DSHEA, pronounced Dee-shay). This legislation defined dietary supplements as distinct from food and drugs, and it allowed them to be sold without a prescription. The passage of DSHEA provided consumers with the right to purchase dietary supplements that they felt would help them attain their personal health goals. At the same time, DSHEA transferred to consumers the responsibility for making informed choices about the supplements that they used. In contrast to prescription and over-thecounter drugs, where effectiveness and safety must be demonstrated prior to marketing of the drugs, premarket approval is not required of manufacturers of dietary supplements. As a result, there is a greater potential risk that dietary supplements may be ineffective, or even harmful, as compared with drugs.

The dietary supplements industry is not unregulated, it is just not regulated to the extent that U.S. consumers have come to expect for prescription drugs. Instead of the drug manufacturer and the physician working to insure that a drug meets the needs of the patient and that it is both safe and effective, consumers must provide these services for themselves with dietary supplements. It is, therefore, important to know the appropriate use of a dietary supplement, the dose at which it is effective, and whether it is likely to interfere with other medications or dietary supplements being taken. It is also important to know that the manufacturer adheres to high quality standards in the preparation of its products.

Supplement Facts Label

To help consumers make informed choices, dietary supplements now contain a supplement facts panel that clearly labels the product as a dietary supplement and gives information such as the amount of a standard dose, the number of recommended doses per day, the list of components (and how much of each is present in a standard dose), and, if the product is a botanical, the Latin name of the plant and the part of the plant used to prepare the product. This latter information is important because the components responsible for a certain health effect may be in one part of the plant but not in other parts. For example, a consumer purchasing ginger to protect against seasickness would want a product prepared from the roots of the plant, where the active components are, and not the leaves.

In addition, DSHEA established standards for terms, such as high potency and antioxidant, and for the types of claims that could be made for a product. Claims that a dietary supplement may help to prevent or cure a disease cannot be made. Such claims are considered health claims and must be reviewed by the Food and Drug Administration for scientific accuracy prior to approval for use on a product label. Manufacturers may, however, use structure/function claims that state that a product can, for example, "help to promote healthy blood levels of cholesterol ," but they may not state that a product "helps to prevent heart disease ." All structure/function claims must be accompanied by the following disclaimer: "This statement has not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease."

Selecting a CAM Modality

When selecting a CAM modality, it is important to have clearly defined health goals. In other words, what are you trying to accomplish, and is this modality an appropriate fit for you? If selecting a therapy, determine if the practitioner of the therapy being considered is a licensed health care practitioner. Licensure does not guarantee the modality will successfully meet one's needs, but it does provide some assurance of training and competency on the part of the practitioner. This information can usually be obtained from the various state boards of medicine, which are responsible for licensing health care professionals.

Selecting quality dietary supplements can be a bit more challenging. Both the natural products industry and the Food and Drug Administration are working to develop uniform standards of quality for dietary supplements. Until these standards are in place, however, consumers must be proactive in determining for themselves what supplements are consistent with their health goals and what manufacturers offer quality products. It is important not to be fooled by hype . Be wary of supplements that sound too good to be true or that promise to cure a medical condition.

Quality natural ingredients and responsible product testing can add significantly to the cost of a dietary supplement. The cheapest supplement is not always the best buy, though a high price does not necessarily guarantee high quality. It is important to investigate the supplement manufacturer whose products are being considered. Manufacturer contact information appears on the supplement facts label. One should inquire whether the manufacturer uses Good Manufacturing Practices, how they ensure the purity of their ingredients, and whether they have their products tested by independent laboratories to verify that the label accurately reflects the product in the supplement container.

Alternative therapies are increasingly being used to complement conventional medicine. The consumer should be knowledgeable of the modality chosen, its intended purpose, and whether it is appropriate for that purpose. In the case of dietary supplements, consumers should educate themselves about the appropriate application for the supplement and the dose that is known to be safe and effective. Although many reputable CAM practitioners and dietary supplement manufacturers exist, consumers should educate themselves about the hallmarks of a quality practitioner or dietary supplement. With CAM modalities in general, and dietary supplements in particular, it is helpful to identify health care professionals who are knowledgeable about CAM and who can provide help in using CAM effectively.

see also Dietary Supplements; Macrobiotic Diet.

Ruth M. DeBusk

Bibliography

Astin, John A. (1998). "Why Patients Use Alternative Medicine: Results of a National Study." Journal of the American Medical Association 279:1548–1553.

Eisenberg, David M.; Davis, Roger B.; Ettner, Susan L.; Appel, Scott; Wilkey, Sonja; Van Rompay, Maria; Kessler, Ronald C. (1998). "Trends in Alternative Medicine Use in the United States, 1990–1997: Results of a Follow-Up National Survey." Journal of the American Medical Association 280:1569–1575.

Eisenberg, David M.; Kessler, Ronald C.; Foster, Cindy; Norlock, Frances E.; Calkins, David R.; and Delbanco, Thomas L. (1993). "Unconventional Medicine in the United States: Prevalence, Costs, and Patterns of Use." New England Journal of Medicine 328:246–252.

Internet Resources

Center for Food Safety and Applied Nutrition. "Dietary Supplements." Available from <http://www.cfsan.fda.gov>

Federation of State Medical Boards. "Member Medical Boards." Available from <http://www.fsmb.org/members.htm>

National Center for Complementary and Alternative Medicine. <http://www.nccam.nih.gov>

Office of Disease Prevention and Health Promotion (1997). "Report of the Commission on Dietary Supplement Labels." Available from <http://web.health.gov/dietsupp>

U.S. Food and Drug Administration (1995). "Dietary Supplement Health and Education Act." Available from <http://www.fda.gov>

Dietary Supplements

The demand for dietary supplements in the United States catapulted what was once a cottage industry into a $14 billion per year business in the year 2000. In 1994, the U.S. Congress formally defined the term dietary supplement as a product taken by mouth that contains a "dietary ingredient" intended to supplement the diet . The dietary ingredients in these products may include vitamins , minerals , herbs, amino acids , enzymes , organ tissues, glandulars, and metabolites . Dietary supplements can also be extracts or concentrates, and may be found in many forms, such as tablets, capsules, liquids, or powders.

The use of dietary supplements is widespread—they are taken by half of American adults. But the use of supplements is not limited to adults. A study published in the November 2001 Journal of the American Dietetic Association showed that dietary supplement use is prevalent among students as well, with 17.6 percent of 1,532 eighth-graders reporting the use of a vitamin-mineral supplement. Herbs, one type of dietary supplement, are widely used throughout the world. In China, traditional medicine encompasses a holistic approach to healing, and herbal remedies are routinely included in self-care. The World Health Organization (WHO) estimates that in developing countries up to 80 percent of indigenous populations rely on herbs for primary health care needs. In France and Germany, 30 to 40 percent of all medical doctors rely on herbal preparations as their primary medicines.

Regulation of Dietary Supplements

In 1994 the U.S. Congress passed the Dietary Supplement Health and Education Act (DSHEA), which President Bill Clinton signed into law the same year. One provision of DSHEA clarified the definition for dietary supplements outlined above. DSHEA also mandated the establishment of the Office of Dietary Supplements (ODS) within the National Institutes of Health. The ODS coordinates research on dietary supplements and acts as a clearinghouse for regulatory issues. It also maintains an excellent resource for consumers, the International Bibliographic Information on Dietary Supplements (IBIDS), which is a database that contains citations published in scientific journals on the topic of dietary supplements. The public can access IBIDS on the ODS website.

DSHEA established a new regulatory framework for supplement safety and for the labeling of dietary supplements by the U.S. Food and Drug Administration (FDA). Dietary supplements are regulated under food law, but with certain provisions that apply only to dietary supplements. For example, dietary supplements escape the stringent approval process that food additives and drugs must go through before being marketed to the public, unless the manufacturer of a dietary supplement makes a claim for therapeutic efficacy .

DSHEA also gave manufacturers the freedom to provide information about product benefits on labels through three types of claims. Health claims describe a relationship between a food substance and a disease or health-related condition. For example, the health claim "diets high in calcium may reduce the risk of osteoporosis " has been authorized by the FDA and may appear on the labels of dietary supplements. Structure function claims may state a benefit related to a nutrient-deficiency disease (such as scurvy , which is caused by a deficiency of vitamin C), as long as the statement tells how widespread the disease is. These claims may also describe the role of a nutrient intended to affect a structure or function—for example, "antioxidants maintain cell integrity," or "calcium builds strong bones." Nutrient content claims describe the level of a nutrient or dietary substance in a product, using FDA-regulated terms such as "good source," "high," or "free." For example, if a label claims a dietary supplement is fat-free, the supplement must contain less than 0.5 grams of fat per serving.

Baby Boomers and Nutritional Supplements

Informed, prosperous, and health-conscious, the baby boomers are known as a generation that plans to fight vigorously against the encroachments of age. During the 1990s, as the boomers began reaching their fifties, they increasingly turned to supplements to ward off osteoporosis, memory loss, and a host of other ailments. With increased demand, the vitamins, minerals, and herbs they sought migrated from health food stores to mass merchandisers. Between 1997 and 2002 the supplement industry experienced a 34 percent jump in sales, to more than $19 billion annually.

—Paula Kepos

However, information on supplement labels cannot be false or misleading. For example, statements that a product will treat, cure, or diagnose a disease are reserved for drugs. That is why the label of the popular herbal extract echinacea may boast that the herb "supports good immune function" but will not claim to "cure your cold."

In Germany, herbs and herbal products are regulated in a different way than in the United States. In 1978, the German Federal Health Agency established the German Commission E to investigate the safety and efficacy of herbal remedies commonly used in Germany. The commission weighed evidence from the literature, from anecdotal reports, and from clinical studies. They subsequently developed monographs on over 400 herbs. These monographs are now used worldwide as essential references on herbal therapy. The commission also established indications (how an herb is used medicinally) and dosage recommendations, resulting in the successful mainstreaming of herbs into medical practice. German physicians frequently prescribe the herbs ginkgo biloba, hawthorn, St. John's wort, horse chestnut, and saw palmetto. Unlike U.S. law, German law allows herb manufacturers to market herbs with drug claims if the herb is proven safe and effective.

Controversies Surrounding the Use of Dietary Supplements

Opponents of DSHEA claim that the issue of public safety is their primary concern. Steven H. Zeisel, of the University of North Carolina School of Public Health and School of Medicine, writes that "DSHEA modifies the regulatory environment so that it becomes possible, even likely, that products will be marketed that inadvertently harm people" (Zeisel, p. 1855). Zeisel believes that the DSHEA legislation makes it easy for small enterprises to market products without investing the time and money needed to prove their product's safety and efficacy. He contrasts the development of a new dietary supplement to that of a new drug or food additive, for which there is a formal process to evaluate safety.

A manufacturer developing a new drug or food additive must conduct safety studies following FDA procedures. Results must be submitted to the FDA for review and approval before the ingredient or drug can be sold to the public. This is not the case for dietary supplements, however, because under DSHEA they are legally in a class by themselves. The FDA must simply be notified of the new product, and the notification must provide information that supports the manufacturer's claim that its product is safe. Once the product is marketed, the FDA is responsible for proving that a dietary supplement is unsafe before it can take action to restrict that product's use or remove it from the marketplace.

Another issue critics of DSHEA cite is the scant quality control of dietary supplements. Quality control is important to assure consumers that a product contains the ingredients stated on the label in the stated amounts. Neither the FDA nor any other federal or state agency routinely tests dietary supplements for quality prior to sale. But some manufacturers of dietary supplements do adhere to Good Manufacturing Practices (GMPs) and make every effort to produce a quality product. Also, the FDA has assisted the industry by proposing GMPs that focus on ensuring the identity, purity, quality, strength, and composition of dietary supplements.

DSHEA supporters fear that increased regulation of dietary supplements will decrease access to beneficial products. National opinion surveys show that many supplement users feel so strongly about the potential health benefits of supplements that they would continue to use them even if the supplements were shown to be ineffective in clinical studies. Consumers value freedom of choice, and many view regulation as an attempt by the government and medical establishment to monopolize treatment options. Clearly, a balance needs to be reached between preserving freedom of choice and ensuring that dietary supplements are safe and effective.

see also Alternative Medicines and Therapies; Food Labels; Health Claims; Quackery; Vitamins, Fat-Soluble; Vitamins, Water-Soluble.

Jackie Shank

Bibliography

Blendon, R. J.; DesRoches, C. M.; Benson, J. M.; Brodie, M.; and Altman, D. E. (2001). "American's Views on the Use and Regulation of Dietary Supplements." Archives of Internal Medicine 161(6):805–10.

Dwyer, Johanna T.; Garceau, Anne O.; Evans, Marguerite; Li, Donglin; Lytle, Leslie; Hoelscher, Deanna; Nicklas, Theresa A.; and Zive, Michelle (2001). "Do Adolescent Vitamin-Mineral Supplement Users Have Better Nutrient Intakes than Nonusers? Observations from the CATCH Tracking Study." Journal of the American Dietetic Association 101(11):1340–1346.

Fleming, Thomas, ed. (1998). PDR for Herbal Medicines. Montvale, NJ: Medical Economics.

Sarubin, Allison (2000). The Health Professional's Guide to Popular Dietary Supplements. Chicago: American Dietetic Association.

Skidmore-Roth, Linda (2001). Mosby's Handbook of Herbs & Natural Supplements. St. Louis, MO: Mosby.

Somer, Elizabeth (1996). The Essential Guide to Vitamins and Minerals, 2nd edition. New York: HarperPerennial.

Zeisel, Steven H. (1999). "Regulation of Nutraceuticals." Science 285:1853–55.

Internet Resources

National Institutes of Health, Office of Dietary Supplements. <http://ods.od.nih.gov>

U.S. Food and Drug Administration Center for Food Safety and Applied Nutrition (2001). "Overview of Dietary Supplements." Available from <http://www.cfsan.fda.gov/~dms>

Dietary Supplements

Dietary supplements are a very broad class of substances that are taken and consumed in the same fashion as food. Such supplements are generally intended to add nutritional value to the diet through their use. Supplements were well understood by native cultures throughout the world for thousands of years prior to the development of the scientific method. Examples include the addition of animal organs to the diets of the hunters of native tribes in early North America, the introduction of the herb ginseng by the Chinese into many foods to provide additional nutrition, and the harvest of guarana by Amazonians to fortify prepared foods.

Perhaps the most enduring symbol of a historic organized dietary supplement practice is the nickname given to British sailors in the seventeenth century; they were called limeys for their consumption of limes to counter the effect of scurvy, a potentially fatal vitamin C deficiency. Scurvy was a constant threat to seamen, who typically existed through long voyages on dried biscuits and salted meats. English sailors did not understand the biological mechanism of the limes that supplemented their diet, but they understood that the technique worked.

The science of diet supplements gained favor in the early part of the twentieth century, as the vitamin B complex began to be isolated in laboratories, starting with thiamine in 1903. Research conducted during World War II, both to assist in providing soldiers in the field with better rations as well as experiments directed to assist prisoners of war with speedier means of recovering lost weight, were a spur to further supplement development.

In the United States and most other countries of the Western world, the science of diet supplements grew into a very robust industry by the early 1990s. The seemingly limitless speed with which society moved fostered a huge fast-food industry, where the desire for convenience dictated the use of processed foods with questionable nutritional value. In many nations, dietary supplements have been promoted as a preventative measure to combat the effects of diseases as diverse as diabetes and macular degeneration, a loss of vision caused by malfunction of the macula, the central part of the retina, attributed to an amino acid deficiency.

In 1994, the United States, through an enactment known as the Dietary Supplement Health and Education Act (DSHEA), established a comprehensive scheme of regulation for the manufacture, distribution, sale, and marketing of all dietary supplements; many countries throughout the world have similar legislation in place.

The DSHEA created the term "dietary ingredient" to describe the component that would make certain kinds of foods dietary supplements, including vitamins (substances that assist in the healthy development and regulation of human metabolism and cell development); minerals (elements that are essential to musculoskeletal growth and function, as well as the operation of the central nervous system; herbs (botanical products that typically are used as sources of vitamins, minerals, or other substances); and amino acids (the central components of proteins used to build and maintain muscle and tissue).

An important and frequently misunderstood distinction is that between a dietary supplement and a drug. A drug is a substance that is either an entire medication, or forms a component of a medication. Although the distinction between drug and supplement may be a fine one in some circumstances, drugs are generally closely regulated regarding use or requiring a prescription from a medical doctor, with the object of curing, treating, or preventing the recurrence of a disease or illness. For this reason, a drug administered by a physician might contain substances that in other circumstances are dietary supplements.

"Dietary supplement" is an umbrella term, one that may include a number of other more general expressions, some of which have meanings that tend to overlap with others. For many years, the phrase "nutritional supplement" has been used interchangeably with dietary supplement, including any food or food-like product that will add nutritional value to a diet. Vitamin supplements are an equally generic description of various kinds of vitamins, either as a single vitamin (such as vitamin C), a vitamin B complex (with the eight members of the complex taken together), or as a multivitamin (with numerous vitamins in varying amounts). Protein supplements are often a reference to amino acid supplements, or inaccurately, to chemically derived substances such as creatine. Like vitamins, mineral supplements refer to single minerals such as calcium, or to multiple minerals.

No matter what kind of descriptors are used to define dietary supplements, these products traditionally had been consumed by both the general population as well as the athletic community. Supplements might be taken to improve general, day-to-day health. A body that has an optimal level of vitamins and minerals, in conjunction with a reasonable balance between carbohydrates, proteins, and fats, will tend to function better and more efficiently. Supplements are taken for a specific physical condition such as to address an iron deficiency (for cases of anemia), or to address a mineral deficiency such as calcium.

Supplements are also ingested as a preventative, such as fiber supplements to act as a defense to bowel or colon cancer, or to fine-tune and bolster athletic performance. For example, an athlete might take electrolytic drinks (containing among other substances sodium and potassium, minerals that are necessary to the function of the neurological and fluid systems) to maintain balance, or take creatine or amino acid supplements to build muscle mass.

Most health and nutritional experts agree that the best way for the body to obtain the benefits of vitamins, minerals, and other dietary substances is through foods obtained through a properly balanced diet, as opposed to taking pill, powder, or other forms of supplements. However, there is no chemical distinction between a compound such as vitamin A in pill form and that contained in foods such as eggs or milk; taken in proper amounts, the impact upon the body will be the same. The chief risk of taking a dietary supplement in the concentrated form of a pill or tablet is the risk that a person might accidentally ingest too much of the supplement, as some vitamins and minerals are toxic in large quantities, such as vitamin A and vitamin D (working in conjunction with calcium). Other supplements can be harmful to the processes of the body, such as using high levels of sodium.

The supplements that are taken for simple health promotion and protection do not specifically target a particular physical condition. These are dietary products intended to supplement existing good health and bodily function, an assurance and a safety net as opposed to a solution. For example, multivitamins are found in various combinations, advertised to supplement either the entire vitamin A through E range, or segments of it. Every vitamin and mineral has a proscribed recommended daily allowance (RDA), and as vitamin C and some of the vitamin B complex are water soluble, they are not stored in the body. Consequently, a supplement may address those shortages.

Herbal products, often sold in the form of teas or beverage ingredients, have a long history as dietary supplements. Preparations made from plants such as ginseng root and ephedra (ma huang) are said to assist with digestive, urinary, and sleep patterns. Also, fresh cultured bacterial yogurt is consumed as a supplement to strengthen the immune system. The mineral zinc is taken as a supplement to strengthen the immune system. In some limited circumstances, even alcohol, as a form of fermented sugar, is properly characterized as a dietary supplement. Alcohol, in limited amounts (less than the equivalent of ten 4-oz units [125 ml] of wine per week), where the person has no other relevant physical restrictions, has been established as a factor in reduced blood pressure and other symptoms of poor cardiovascular health.

Many dietary supplements are taken to help eliminate an existing physical condition. Bowel disorders and accompanying constipation are problems that are common with persons who eat inordinate amounts of highly processed foods. The gastrointestinal system has evolved to require roughage, or fiber, to assist in the waste disposal process through the bowels. Fiber powder supplements have been developed, using a variety of natural fibers and herbs, to compensate for dietary shortfalls.

Menstrual pain is a reality for millions of women. The dietary supplements that include combinations of vitamin B6, calcium, and magnesium are taken to help the body create its own relief from menstrual pain. Osteoporosis, the thinning and weakening of skeletal bone structures, is another condition that typically affects females, as its origins are related to calcium depletion tied to the nursing of children, combined by the effects of menopause. Calcium supplements are a common addition to the diets of persons with osteoporosis.

Many dietary supplements are taken for the express purpose of preventing the onset of a particular ailment, such as cancer and heart disease. Prevailing medical and nutritional theory indicates that a balanced diet, regular exercise, and the avoidance of unhealthy habits such as smoking, recreational drug use, and excessive alcohol consumption, are the most logical route to long-term health. The medical evidence is equally clear that in most cases there is not likelihood of harm from the ingestion of dietary supplements that appear to mimic the other components of a proper diet.

The dietary supplements used by athletes tend to have a specific performance focus, as opposed to being engaged as a preventative measure. Athletes, especially as they approach elite levels of training and performance, encounter progressively greater physical challenges that tax their bodies and tend to increase all dietary requirements. In events where the margin between victory and defeat may be measured in fractions of seconds or in inches or centimeters, the athlete, through a carefully monitored diet, must ensure that every conceivable body function is capable of being engaged to a maximum level.

Athletes will notice through performance whether they have optimum vitamin and mineral levels. Further, the recovery time that they experience after a difficult training session or a competition is a powerful indicator of nutritional health. The athletic dietary supplements are generally taken on a daily basis. In training and competitions, for marathon runners or triathletes, supplements are intended to replace carbohydrate stores consumed during the event as well as electrolytes such as sodium and potassium. These supplements may be consumed as fluids, energy bars, or gels. Supplements provide post-training or competition boosts to the bodily stores to assist in recovery. Protein or creatine supplements assist in the development of muscle mass.

see also Glutamine supplementation; Minerals; Protein supplements; Supplement contamination.